Date | May 2019 | Marks available | 2 | Reference code | 19M.2.SL.TZ1.T_6 |
Level | Standard Level | Paper | Paper 2 | Time zone | Time zone 1 |
Command term | Write down | Question number | T_6 | Adapted from | N/A |
Question
The function has a local maximum and a local minimum. The local maximum is at .
Show that .
Find the coordinates of the local minimum.
Write down the interval where the gradient of the graph of is negative.
Determine the equation of the normal at in the form .
Markscheme
* This question is from an exam for a previous syllabus, and may contain minor differences in marking or structure.
(A1)(A1)(A1)
Note: Award (A1) for each correct term. Award at most (A1)(A1)(A0) if additional terms are seen or for an answer . If their derivative is seen in parts (b), (c) or (d) and not in part (a), award at most (A1)(A1)(A0).
(M1)(M1)
Note: Award (M1) for substituting in into their derivative and (M1) for setting it equal to zero. Substituting invalidates the process, award at most (A1)(A1)(A1)(M0)(M0).
(AG)
Note: For the final (M1) to be awarded, no incorrect working must be seen, and must lead to the conclusion . The final (AG) must be seen.
[5 marks]
(2, −2.33) OR (A1)(A1)
Note: Award (A1) for each correct coordinate. Award (A0)(A1) if parentheses are missing. Accept , . Award (M1)(A0) for their derivative, a quadratic expression with –6 substituted for , equated to zero but leading to an incorrect answer.
[2 marks]
(A1)(ft)(A1)
Note: Award (A1) for , (A1)(ft) for . Follow through for their "2" in part (b). It is possible to award (A0)(A1). For award (A1)(A0). Accept equivalent notation such as (−3, 2). Award (A0)(A1)(ft) for .
[2 marks]
−4 (A1)(ft)
Note: Award (A1)(ft) for the gradient of the tangent seen. If an incorrect derivative was used in part (a), then working for their must be seen. Follow through from their derivative in part (a).
gradient of normal is (A1)(ft)
Note: Award (A1)(ft) for the negative reciprocal of their gradient of tangent. Follow through within this part. Award (G2) for an unsupported gradient of the normal.
(A1)
Note: Award (A1) for (16.3333…) seen.
OR (M1)
Note: Award (M1) for substituting their normal gradient into equation of line formula.
OR (A1)(ft)(G4)
Note: Award (G4) for the correct equation of line in correct form without any prior working. The final (A1)(ft) is contingent on and .
[5 marks]